The subject invention relates to a new and improved zero insertion force pin grid array socket for temporarily connecting the conductive pins of an electrical component and a printed circuit board during a test and evaluation procedure. Further, the subject invention relates to a new and improved electrical connector having preloaded contact beams.
To determine whether or not an electrical component, such as an integrated circuit pack, will perform reliably it is necessary to test and evaluate each device on a printed circuit board. In the past testing involved forcing leads on a device into a receptacle having spring loaded contacts which were connectible to circuitry. This type of connection required the exertion of considerable pressure.
The necessity for the exertion of considerable pressure to urge the leads into the contacts was undesirable. In applications that involved components with a substantial number of leads it became exceedingly difficult to force the leads into a connector. Further, the exertion of substantial pressure upon the leads of the component into the spring loaded contacts often resulted in breaking or bending the leads.
Accordingly, in the prior art various improved connectors have been developed which are designed to reduce or eliminate the insertion force required to urge the leads of an electrical component into the connector. An example of a low insertion force socket is disclosed in U.S. Pat. No. 3,763,459 which issued to Millis on Oct. 2 1973 entitled "Plug in Type Socket For Testing Semiconductors". The socket disclosed in U.S. Pat. No. 3,763,459 comprises a generally rectangular upper section and a generally rectangular lower section with a generally rectangular longitudinally movable center section therebetween. The upper section includes a plurality of openings for receiving the pins of an integrated circuit pack. The lower section includes a corresponding plurality of electrical contacts, each having a pair of resilient contact beams and a solder tail. The resilient contact beams of the electrical contacts extend through the center section so that they are each aligned within a respective channel. The solder tail of each of the electrical contacts extends through the exposed surface of the lower portion so as to connect with a printed circuit board.
The socket disclosed in U.S. Pat. No. 3,763,459, is operated by inserting the conductive pins of an integrated circuit pack into the receptacle openings in the upper member such that they extend into the center section of the socket. Thereafter, a cranked actuator is rotated to cause the center section of the socket to slide longitudinally, relative to the upper and lower members. Simultaneously, the walls of the channels disposed within the center section exert a biasing force on the arms of the contacts such that they make electrical connection with the conductive pins of the integrated circuit pack. Upon completion of a test the crank can be oppositely rotated to permit the center portion to slide back to its normal unlocked position whereby the resilient contact arms return to their relaxed condition.
Another form of low insertion force test socket is disclosed in U.S. Pat. No. 4,648,669 which issued to Marks et al., on Mar. 10, 1987 entitled "Removable Retaining And Guide Means For Electrical Sockets". The latter discloses an electrical socket comprising a generally rectangular non-conductive plastic base member with a generally rectangular non-conductive plastic upper member slidably movable thereupon. The upper member of the socket includes a plurality of pin receiving apertures disposed in a grid array. The base member includes a plurality of electrical connectors which are disclosed in U.S. Pat. No. 4,498,725 which issued to Bright et al., on Feb. 12, 1985 entitled "Electrical Connector". The connector depicted in U.S. Pat. No. 4,498,725 includes a pair of generally 7-shaped resilient contact beams and a solder tail extending outwardly from one of the beams. The plurality of electrical connectors are disposed within a plurality of corresponding walled cavities defined within the base member such that the walls of the cavities supply the resilient contact beams of each of the electrical connectors with an inwardly biased contact force. The socket further includes a generally L-shaped cammed actuator disposed in a journal in the base member.
The upper member and the lower member of the socket disclosed in U.S. Pat. No. 4,648,669 include a plurality of interfingering hole-containing blocks disposed intermediate, and extending outwardly from, the lateral edges of the upper member and base member respectively. The interfingering blocks extend beyond the planar area of the base member and lid member, thus necessarily increasing the envelope of the socket on a circuit board. A plurality of cylindrical rigid retaining and guide pins, having upturned ends, are forcibly inserted, parallel to the plane of the socket, into the holes in the interfingering blocks, thereby connecting the upper member to the base member and guiding it thereon. The rigid retaining and guide pins may be removed in order to replace a broken electrical connector. However, repeated removal of the pins will have a detrimental effect on the plastic socket, thus eventually the socket will have to be discarded. In another embodiment of the socket disclosed in U.S. Pat. No. 4,648,669 the upper member is connected to the base member by a U-shaped rigid retaining member.
Accordingly, it is an object of the subject invention to provide a new and improved zero insertion force pin grid array test socket having a plurality of flexible non-destructive retaining and guide means.
A further object of the subject invention is to provide a flexible retaining and guide means that does not increase the size or envelope of a pin grid array test socket.
A further object of the subject invention is to provide a flexible retaining and guide means for a pin grid array test socket which is inexpensive to manufacture.
A further object of the subject invention is to provide a flexible retaining and guide means for a pin grid array test socket which is disposable.
A further object of the subject invention is to provide a new and improved electrical connector having a pair of neutrally inwardly biased contact beams.
A further object of the subject invention is to provide a new and improved electrical connector that is inexpensive to manufacture.